Minimally invasive surgical procedures have numerous advantages, such as a reduced traumatization and a more rapid recovery on the part of the patient, reduced demands on anesthesia, briefer patient stays in the operating room, and subsequently lower costs in the clinic as well as in general. An endoscope used in minimally invasive surgery must fulfill numerous requirements simultaneously. In particular, it must include strong reliability and/or availability and a long useful lifetime, despite the thermal impact from autoclaving following each use.
Variable view endoscopes are already described in the art in U.S. Pat. No. 6,110,105 A, U.S. Pat. No. 6,638,216 B1, US 2004/0236183 A1, and WO 01/22865 A1. Variable view endoscopes for technical, non-medical applications (also called boroscopes) are already commercially available. Endoscopes for medical applications with a line of vision that can vary over a wide angle are not yet available, however. The reason, among other factors, is found in the interface between the mantle or housing of the endoscope and the transparent window, which must be curved to achieve a wide angle. This interface must also remain hermetically insulated even after many cycles of preparation, particularly autoclaving, in order to prevent penetration of moisture into the interior of the endoscope and the damaging of the lens by moisture penetration.
In particular, the applicant has been obliged to observe that in other types of endoscopes with plane, circular, or elliptical windows, proven joining techniques for durable mechanical connection of the window with the housing or mantle of the endoscope with curved windows cannot be applied. Because of the curvature, the comparatively great total surface, and a clearly non-elliptical contour, the temperatures and temperature changes and resulting variable length-wise extension with conventional material pairings in a joining process as well as in a customary autoclaving process require mechanical tensions that, after a brief time, lead to fissures or fractures in the window or in the joining seam. Investigations have shown that even with a geometric modification of components made of customary materials, significant tensions arise in the joining process that can result in fissures or fractures of the window, even when this process is withstood without damage, at the latest during preparation.
One object of the present invention consists in creating an improved endoscope and an improved process to manufacture an endoscope with a window, in particular a curved window.